Graphene Nanoribbons Conduct Electricity

Walt de Heer, a professor in the School of Physics at the Georgia Institute of Technology says his team has developed thin, conductive nanoribbons featuring quantum ballistic properties.

This method of templated growth to create nanoribbons from epitaxial graphene has created structures measuring 15 to 40nanometers wide. The structures conduct electricity spontaneously. They could connect graphene devices fabricated from traditional methods.

This discovery had been published in the October 3 online edition of Nature Nanotechnology. It helps develop epitaxial graphene designs having smooth edges. The narrow ribbons act like a metal. Electrons can travel through them without dispersing, like in carbon nanotubes.

De Heer discussed this discovery on March 21 at the American Physical Society's Meeting in Dallas. The team received funding from the Materials Research Science and Engineering Center (MRSEC) supported by the National Science Foundation. Edges that impact the properties of grapheme have been removed. The edges blend into the silicon carbide.

Patterns are etched into the silicon carbide surfaces, on which epitaxial graphene is cultivated. The motifs become templates that monitor the graphene growth and allow nanoribbons of specific widths and shapes to be created without requiring cutting that causes rough edges. Traditional microelectronics methods were used initially to etch nano-steps or contours into a silicon carbide wafer. The wafer surface had been flattened. The contoured wafer was heated to about 1,500°C, leading to melting that smoothens rough edges caused by etching. Graphene was cultivated form silicon carbide by removing the silicon from the surface. The heating time was restricted to allow graphene to grow on certain areas of the contours.

The nanoribbon’s width depends on the contour’s depth leading to accurate monitoring. Multiple etching leads to complicated structures. Quantum products will be nano-sized and power efficient. Epitaxial graphene will be suitable for quantum products.

Graphene oxide membranes have been receiving attention for their extremely powerful separation abilities and the ease at which it can be modified, allowing for membrane permittivity to be fine-tuned. These membranes show the potential to be used for water purification, ‘green’ gas purification and greenhouse gas capture.